GIRAFFE Exposure Time Calculator

Optical Multi-Object Spectroscopy Mode Version P109
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NOTE: As announced here, the fibre spatial profiles were improved in February 2015, and are now narrower and peak at higher ADU levels (10-30% higher). This will be helpful for programmes with faint targets. The ETC will issue a warning if your observations reach close to saturation. In this case, please consider shorter exposure times and/or multiple exposures. Typically this should happen only if your targets are brighter than V≈11.

Source Model

Input Flux Distribution:
Uniform (constant with wavelength) Target Magnitude and System:
=  Vega
Magnitudes are given per arcsec2
for extended sources.
Template Spectrum:
Redshift z =
Blackbody: Temperature : K
Source Geometry: Point Source  
Extended Source

Sky Conditions

Moon FLI: Airmass:
Time step forward/back

Target coordinates Name or ID:  
α      δ     
UT rise
Hour Angle azimuth altitude zenith distance airmass FLI moon/sun
phase angle
An advanced almanac is available in the ESO SkyCalc sky model calculator
PWV:     mm     Probability % of realising the PWV ≤ 10.00 mm
Seeing/Image Quality:
Turbulence Category:   (FWHM of the atmospheric PSF outside the telescope at zenith at 500 nm)
IQ: arcsec FWHM at the airmass and reference wavelength
              The corresponding seeing and turbulence category will be indicated in the output page
Image Quality is not a parameter in AO modes

Instrument Setup

Fiber Mode (Sky Sampling):

MEDUSA mode only: Object-fiber displacement: arcsec (range: [ 0.00 ; 0.60 ]).
In other modes, this value is irrelevant and has no effect.

High resolution: Setup (λc):
Low resolution: Setup (λc):
Detector: Carreras CCD mode:



Exposure Time: s

Plots: Toggle All / No Plots

Object Spectrum
Sky Spectrum
Observed Object+Sky Spectrum
Input spectrum in physical units
Total Efficiency and Wavelength Range